1. Field of the Invention
The present invention relates to a near infrared (NIR) imaging lens assembly, and more particularly, to an NIR imaging lens assembly which is applied to an electronic product.
2. Description of the Prior Art
The wavelength range of visible light is generally between 400 and 700 nm.
Infrared light has a wavelength range between 700 and 106 nm and is not detectable with the naked eye, wherein the region from about 700 to 2000 nm is called the NIR wavelength range. Since NIR light has advantages of being less likely to be affected by interferences, lower cost and power consumption, and being highly secretive (less likely to be recognized with the naked eye), it is applied in many electronic technologies to develop various electronic products, such as remote control devices, infrared monitors and infrared detector systems. Also, as interactive video games are getting popular in recent years, more and more video game products with interactive detection features can be found on the market; NIR imaging technology may be used in those products to detect movements of the player, thereby achieving the interactive entertainment features.
Typically, a filter is added into an NIR imaging assembly to prevent light in the other wavelength ranges from interfering the response of the system. With the use of a filter, only light in a desirable wavelength range can pass through the system, while light in the other wavelength ranges is cut off. However, a filter that can concurrently cut off light near both the longer and shorter wavelength ends of a desirable region requires a more complex manufacturing process. Moreover, such a filter generally has a greater thickness, which tends to increase the total track length of the system as well as its production cost.